Ceramic colors

Ceramic colors or stains consist mainly of pigments, glaze or body, and opacifiers. They are used for the decoration of porcelain, earthenware bone china and other ceramics. Glazes and enamels are the main application systems for ceramic colors. Pigments are the color giving components in the composition of a ceramic color. High temperature and chemical stability as well as high tinting strength are characteristics of stains. Technically important ceramic colors are cadmium sulfide and sulfoselenides (occluded in zircon), metals such as gold, silver, platinum, and copper (as colloidal particles), metal oxides (α-Fe2O3, Cr2O3, CuO, Co3O4/CoO, MnO2/Mn2O3, and NiO/Ni2O3), mixed metal oxides and silicates, zirconia-based and zircon-based compositions. Ceramic colors are often produced using solid state reactions.

Radiometric Calibration Targets for the Mastcam-Z Camera on the Mars 2020 Rover Mission

The Mastcam-Z Camera is a stereoscopic, multispectral camera with zoom capability on NASA’s Mars-2020 Perseverance rover. The Mastcam-Z relies on a set of two deck-mounted radiometric calibration targets to validate camera performance and to provide an instantaneous estimate of local irradiance and allow conversion of image data to units of reflectance (R∗ or I/F) on a tactical timescale. Here, we describe the heritage, design, and optical characterization of these targets and discuss their use during rover operations. The Mastcam-Z primary calibration target inherits features of camera calibration targets on the Mars Exploration Rovers, Phoenix and Mars Science Laboratory missions. This target will be regularly imaged during flight to accompany multispectral observations of the martian surface. The primary target consists of a gold-plated aluminum base, eight strong hollow-cylinder Sm2Co17 alloy permanent magnets mounted in the base, eight ceramic color and grayscale patches mounted over the magnets, four concentric, ceramic grayscale rings and a central aluminum shadow post (gnomon) painted with an IR-black paint. The magnets are expected to keep the central area of each patch relatively free of Martian aeolian dust. The Mastcam-Z secondary calibration target is a simple angled aluminum shelf carrying seven vertically mounted ceramic color and grayscale chips and seven identical, but horizontally mounted ceramic chips. The secondary target is intended to augment and validate the calibration-related information derived from the primary target. The Mastcam-Z radiometric calibration targets are critically important to achieving Mastcam-Z science objectives for spectroscopy and photometric properties.

Effect of different bleaching agents on the surface roughness and color stability of feldspathic porcelain

Objective: The aim of this study was to evaluate the effect of different bleaching agents on the surface roughness and color stability of feldspathic porcelain. Material and Methods: In this study, totally 40 disc-shaped Noritake and Ceramco 3 feldspathic porcelain and two bleaching agents (Opalescence Boost and Opalescence Pf) were used. Bleaching agents were exposed to specimens according to their protocol. Then, the surface roughness of the specimens was evaluated with profilometer and the color of the specimens was recorded by colorimeter. Statistical analysis of the data was performed with IBM SPSS Statistics 20. Results: The results showed that that there were statistically significant differences between the bleaching agents on the surface roughness of feldspathic porcelain (p<0.05). However, there were no statistically significant differences between the bleaching agents on the color stability of feldspathic porcelain (p>0.05). Conclusion: The obtained data presented that the bleaching agents increased the surface roughness and not affect the color stability of the feldspathic porcelain.KeywordsBleaching; Ceramic; Color; Surface roughness.

Synthesis of Spinel Color Pigments from Aluminum Dross Waste

Spinel-based ceramic color pigments were successfully synthesized from utilization of aluminum dross waste and relevant oxide precursors by solid-state processing. Cobalt ions were selected as a chromophore to produce blue pigments. The conventional oxide route was also carried out for comparison purposes. The spinel phase readily formed when fired at 1100 °C; longer duration yielded a higher degree of purity. No preferential orientation of XRD reflection was observed, indicating random crystallographic arrangement. Phase formation was also confirmed by Fourier Transformed Infrared Spectroscopy (FTIR) which displayed both Co-O tetrahedral and Al-O octahedral which are the main framework for a spinel crystal. Slightly sharper FTIR peaks for the dross route compared to those from the oxide route suggest a difference in crystallinity between the two with different precursors. The particle size distribution was relatively wide (5 – 30 micron), possibly due to a crude nature of the dross precursor. The UV-vis spectra showed absorption in the range of 450-550 nm which is associated with the blue color caused by a shift of the 3d7 electrons of Co2+. The obtained dross-route pigments possessed both a and b color parameters (a = -2.3 to-2.6; b = -3.4 to-4.0) in the negative territory, implying greenness and blueness respectively. The L values were in the 20-30 range. When incorporating into practical glazes, the b parameters unexpectedly became more negative, indicating an even deeper blue tone. This result suggested a high potential for utilization of this dross waste as an alternative precursor source for sustainable production of spinel ceramic pigments.